A Comparison of Drill and Broadcast Planting Methods for Biomass Production of Two Legume Cover Crops

Ricardo St Aime,William C Bridges,Sruthi Narayanan,Enoch Noh

doi:10.3390/agronomy12010079

Abstract

The effects of drill and broadcast planting methods on cover crop biomass production depend on various environmental and operational factors. We investigated whether drilling and broadcasting result in different amounts of biomass production by crimson clover (Trifolium incarnatum L.) and hairy vetch (Vicia villosa Roth) in the upstate of South Carolina, and results vary when seeding rates are increased by 50% from the standard value (22.4 kg ha−1). Field trials were conducted during the fall–winter of 2019–2020 (season one) and 2020–2021 (season two) at the Piedmont Research and Education Center in Pendleton, SC, USA. Cover crop (hairy vetch, crimson clover), planting method (broadcast, drill), and seeding rate (standard, high) treatments were arranged as a 2 × 2 × 2 factorial in both years. Aboveground biomass was measured after 22.5 weeks from planting. At standard seeding rates, crimson clover produced a higher biomass when drilled, rather than broadcasted, whereas biomass production did not vary for hairy vetch. Even with 50% higher seeding rates, broadcasting did not always produce the same biomass as that of drilling for crimson clover. Our results suggest that the advantage of drilling over broadcasting depends upon the cover crop species, as crimson clover responds well to drilling, whereas hairy vetch does not.

Highlights

Planting strategies that improve cover crop stand establishment and biomass production are critical to ensure cover crop benefits, such as weed suppression, nutrient scavenging, and erosion control [1]
Our study was motivated by the need to find effective cover crop planting strategies for the southeastern U.S The objective of this study was to evaluate biomass production of two legume cover crops: crimson clover (Trifolium incarnatum L.) and hairy vetch (Vicia villosa Roth), under two different planting methods and seeding rates
The cover crops evaluated in this study, crimson clover and hairy vetch, are common winter cover crops in the southeastern U.S With its rapid and robust growth, crimson clover serves as a weed-suppressing green manure and staple forage crop and provides early spring nitrogen for full-season crops [12]

Summary

Introduction

Planting strategies that improve cover crop stand establishment and biomass production are critical to ensure cover crop benefits, such as weed suppression, nutrient scavenging, and erosion control [1]. Drilling and broadcasting are common planting methods for cover crops [2,3]. A recent survey in Nebraska reported that more than 65% farmers preferred drilling as the cover crop establishment method after harvesting a cash crop [5]. Broadcasting of cover crop seeds is usually accomplished through centrifugal spreaders that hurl seeds horizontally onto the soil’s surface or through implements attached to tractors or aircraft that drop seeds vertically onto the soil [1]. Aerial or ground broadcast methods are sometimes followed by a tillage operation to incorporate the seed into the soil. Farmers skip the incorporation operation when soil is too wet to get machinery into the field or when cover crops are inter-seeded with a standing cash crop [6]

Objectives

Methods

Results

Conclusion